Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

A stator winding is configured by connecting a first three-phase stator
winding and a second three-phase stator winding in parallel. A
U1-phase winding of the first three-phase stator winding is
configured by connecting a U1-1-phase winding portion and a
U1-2-phase winding portion in series, and a U2-phase winding of
the second three-phase stator winding is configured by connecting a
U2-1-phase winding portion and a U2-2-phase winding portion in
series. The U1-1-phase winding portion and the U2-2-phase
winding portion are m-turn wave windings, and the U2-1-phase winding
portion and the U1-2-phase winding portion are n-turn wave windings
(where n does not equal m). The U1-1-phase winding portion and the
U2-1-phase winding portion are mounted into a first slot group, and
the U1-2-phase winding portion and the U2-2-phase winding
portion are mounted into a second slot group.

Claims:

1. A rotary electric machine comprising: a rotor that is rotatably
supported by a housing; and a stator comprising: a stator core in which
slots are formed at a ratio of two slots per phase per pole; and a first
three-phase stator winding and a second three-phase stator winding that
are mounted into said stator core, said stator being supported by said
housing so as to surround said rotor, wherein: said first three-phase
stator winding is configured by wye-connecting a U1-phase winding, a
V1-phase winding, and a W1-phase winding; said second
three-phase stator winding is configured by wye-connecting a
U2-phase winding, a V2-phase winding, and a W2-phase
winding; said U1-phase winding is configured by connecting a
U1-1-phase winding portion and a U1-2-phase winding portion in
series; said V1-phase winding is configured by connecting a
V1-1-phase winding portion and a V1-2-phase winding portion in
series; said W1-phase winding is configured by connecting a
W1-1-phase winding portion and a W1-2-phase winding portion in
series; said U2-phase winding is configured by connecting a
U2-1-phase winding portion and a U2-2-phase winding portion in
series; said V2-phase winding is configured by connecting a
V2-1-phase winding portion and a V2-2-phase winding portion in
series; said W2-phase winding is configured by connecting a
W2-1-phase winding portion and a W2-2-phase winding portion in
series; said U1-1-phase winding portion and said U2-1-phase
winding portion are mounted into a first slot group that is constituted
by said slots at intervals of six slots; said U1-2-phase winding
portion and said U2-2-phase winding portion are mounted into a
second slot group that is constituted by said slots at intervals of six
slots and that is adjacent to said first slot group; said V1-1-phase
winding portion and said V2-1-phase winding portion are mounted into
a third slot group that is constituted by said slots at intervals of six
slots; said V1-2-phase winding portion and said V2-2-phase
winding portion are mounted into a fourth slot group that is constituted
by said slots at intervals of six slots and that is adjacent to said
third slot group; said W1-1-phase winding portion and said
W2-1-phase winding portion are mounted into a fifth slot group that
is constituted by said slots at intervals of six slots; said
W1-2-phase winding portion and said W2-2-phase winding portion
are mounted into a sixth slot group that is constituted by said slots at
intervals of six slots and that is adjacent to said fifth slot group;
said U1-1-phase winding portion, said U2-2-phase winding
portion, said V1-1-phase winding portion, said V2-2-phase
winding portion, said W1-1-phase winding portion, and said
W2-2-phase winding portion are configured by winding conductor wires
that have an identical cross-sectional shape into respective wave
windings in said slots at intervals of six slots for m turns (where m is
an integer); said U1-2-phase winding portion, said U2-1-phase
winding portion, said V1-2-phase winding portion, said
V2-1-phase winding portion, said W1-2-phase winding portion,
and said W2-1-phase winding portion are configured by winding said
conductor wires into respective wave windings in said slots at intervals
of six slots for n turns (where n is an integer that is different than
m); and said first three-phase stator winding and said second three-phase
stator winding are connected in parallel by connecting an output end of
said U1-phase winding and an output end of said U2-phase
winding, by connecting an output end of said V1-phase winding and an
output end of said V2-phase winding, and by connecting an output end
of said W1-phase winding and an output end of said W2-phase
winding.

2. A rotary electric machine according to claim 1, wherein a neutral
point of said first three-phase stator winding and a neutral point of
said second three-phase stator winding are not connected.

Description:

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a rotary electric machine such as
an automotive alternator, and particularly relates to a mounting
construction for a stator winding that is wound into a wave winding in a
stator core in which slots are formed at a ratio of two slots per phase
per pole.

[0003] 2. Description of the Related Art

[0004] In conventional rotary electric machines, a stator winding is
configured by wye-connecting a U-phase winding, a V-phase winding, and a
W-phase winding in each of which a first winding and a second winding
that have a phase difference of 30 electrical degrees from each other are
connected in series, and the first winding and the second winding are
each configured by connecting a plurality of windings in parallel (see
Patent Literature 1, for example).

[0006] In conventional rotary electric machines according to Patent
Literature 1, because the plurality of windings that constitute the first
winding and the second winding are concentrated windings, turn counts of
the windings can be changed easily. Thus, problems with cyclic currents
in parallel circuit portions can easily be solved by making the turn
counts of the plurality of windings that are connected in parallel equal.
In order to achieve desired output characteristics, the turn count
between the first winding and the second winding that are connected in
series must also be changed, but that requirement can be met easily by
changing the turn counts of the windings that constitute the first
winding and the turn counts of the windings that constitute the second
winding.

[0007] Even if the plurality of windings that constitute the first winding
and the second winding are constituted by wave windings instead of
concentrated windings, problems with the generation of cyclic currents in
the parallel circuit portions can be solved by making the turn counts of
the plurality of windings that are connected in parallel equal, and
predetermined output characteristics can be achieved by changing the turn
counts between the first winding and the second winding that are
connected in series.

[0008] Now, let us assume that the first winding is configured by
connecting two four-turn wave windings in parallel, and the second
winding is configured by connecting two three-turn wave windings in
parallel. In that case, eight conductor wires are housed in each of the
slots in which the first winding is mounted, and six conductor wires are
housed in each of the slots in which the second winding is mounted. Thus,
the number of conductor wires that are housed in the slots is different
in each slot, and one disadvantage has been that unevenness occurs on the
inner circumferential surfaces of the coil end groups of the stator
winding, generating loud wind-splitting noise with the rotor.

SUMMARY OF THE INVENTION

[0009] The present invention aims to solve the above problems and an
object of the present invention is to provide a rotary electric machine
in which phase windings are configured by connecting in series two
winding portions that have different turn counts to increase output, and
in which the formation of unevenness on inner circumferential surfaces of
coil end groups is suppressed to enable wind-splitting noise to be
reduced.

[0010] In order to achieve the above object, according to one aspect of
the present invention, there is provided a rotary electric machine
including: a rotor that is rotatably supported by a housing; and a stator
including: a stator core in which slots are formed at a ratio of two
slots per phase per pole; and a first three-phase stator winding and a
second three-phase stator winding that are mounted into the stator core,
the stator being supported by the housing so as to surround the rotor.
The first three-phase stator winding is configured by wye-connecting a
U1-phase winding, a V1-phase winding, and a W1-phase
winding, and the second three-phase stator winding is configured by
wye-connecting a U2-phase winding, a V2-phase winding, and a
W2-phase winding. The U1-phase winding is configured by
connecting a U1-1-phase winding portion and a U1-2-phase
winding portion in series, the V1-phase winding is configured by
connecting a V1-1-phase winding portion and a V1-2-phase
winding portion in series, the W1-phase winding is configured by
connecting a W1-1-phase winding portion and a W1-2-phase
winding portion in series, the U2-phase winding is configured by
connecting a U2-1-phase winding portion and a U2-2-phase
winding portion in series, the V2-phase winding is configured by
connecting a V2-1-phase winding portion and a V2-2-phase
winding portion in series, and the W2-phase winding is configured by
connecting a W2-1-phase winding portion and a W2-2-phase
winding portion in series. The U1-1-phase winding portion and the
U2-1-phase winding portion are mounted into a first slot group that
is constituted by the slots at intervals of six slots, the
U1-2-phase winding portion and the U2-2-phase winding portion
are mounted into a second slot group that is constituted by the slots at
intervals of six slots and that is adjacent to the first slot group, the
V1-1-phase winding portion and the V2-1-phase winding portion
are mounted into a third slot group that is constituted by the slots at
intervals of six slots, the V1-2-phase winding portion and the
V2-2-phase winding portion are mounted into a fourth slot group that
is constituted by the slots at intervals of six slots and that is
adjacent to the third slot group, the W1-1-phase winding portion and
the W2-1-phase winding portion are mounted into a fifth slot group
that is constituted by the slots at intervals of six slots, and the
W1-2-phase winding portion and the W2-2-phase winding portion
are mounted into a sixth slot group that is constituted by the slots at
intervals of six slots and that is adjacent to the fifth slot group. The
U1-1-phase winding portion, the U2-2-phase winding portion, the
V1-1-phase winding portion, the V2-2-phase winding portion, the
W1-1-phase winding portion, and the W2-2-phase winding portion
are configured by winding conductor wires that have an identical
cross-sectional shape into respective wave windings in the slots at
intervals of six slots for m turns (where m is an integer), and the
U1-2-phase winding portion, the U2-1-phase winding portion, the
V1-2-phase winding portion, the V2-1-phase winding portion, the
W1-2-phase winding portion, and the W2-1-phase winding portion
are configured by winding the conductor wires into respective wave
windings in the slots at intervals of six slots for n turns (where n is
an integer that is different than m). The first three-phase stator
winding and the second three-phase stator winding are connected in
parallel by connecting an output end of the U1-phase winding and an
output end of the U2-phase winding, by connecting an output end of
the V1-phase winding and an output end of the V2-phase winding,
and by connecting an output end of the W1-phase winding and an
output end of the W2-phase winding.

[0011] According to the present invention, the U1-1-phase winding
portion that constitutes the U1-phase winding and the
U2-1-phase winding portion that constitutes the U2-phase
winding are wound into the first slot group, and the U1-2-phase
winding portion that constitutes the U1-phase winding and the
U2-2-phase winding portion that constitutes the U2-phase
winding are wound into the second slot group. Thus, the number of
conductor wires that are housed in each of the slots of the first slot
group is (m+n), and the number of conductor wires that are housed in each
of the slots of the second slot group is (m+n). Thus, the number of
conductor wires that are housed in each of the slots is equal,
suppressing formation of unevenness on inner circumferential surfaces of
the coil end groups of the stator winding. Generation of wind-splitting
noise that results from interference between the rotating rotor and the
inner circumferential surfaces of the coil end groups is thereby
suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a longitudinal cross section that shows an automotive
alternator according to a preferred embodiment of the present invention;

[0013]FIG. 2 is an electrical circuit diagram for the automotive
alternator according to the preferred embodiment of the present
invention;

[0014] FIG. 3 is a connection diagram for a stator winding in the
automotive alternator according to the preferred embodiment of the
present invention;

[0015] FIG. 4 is an end elevation that shows a stator core that is used in
the automotive alternator according to the preferred embodiment of the
present invention;

[0016] FIG. 5 is a partial end elevation that explains a state in which
conductor wires are mounted into the stator core in the automotive
alternator according to the preferred embodiment of the present
invention;

[0017]FIG. 6 is a graph that shows measured results of output
characteristics of the automotive alternator according to the preferred
embodiment of the present invention;

[0018] FIG. 7 is a connection diagram for a stator winding according to a
comparative example; and

[0019] FIG. 8 is a partial end elevation that explains a state in which
conductor wires are mounted into a stator core in an automotive
alternator according to the comparative example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] A preferred embodiment of the present invention will now be
explained with reference to the drawings.

[0021] FIG. 1 is a longitudinal cross section that shows an automotive
alternator according to a preferred embodiment of the present invention,
FIG. 2 is an electrical circuit diagram for the automotive alternator
according to the preferred embodiment of the present invention, FIG. 3 is
a connection diagram for a stator winding in the automotive alternator
according to the preferred embodiment of the present invention, FIG. 4 is
an end elevation that shows a stator core that is used in the automotive
alternator according to the preferred embodiment of the present
invention, and FIG. 5 is a partial end elevation that explains a state in
which conductor wires are mounted into the stator core in the automotive
alternator according to the preferred embodiment of the present
invention. Moreover, 1, 7, etc., through 67 in FIG. 4 represent slot
numbers. FIG. 5 represents a state in which an annular stator core is cut
open and spread out in a plane.

[0022] In FIG. 1, an automotive alternator 1 that functions as a rotary
electric machine includes: a housing 4 that is constituted by a front
bracket 2 and a rear bracket 3 that are each approximately bowl-shaped
and made of aluminum; a shaft 6 that is rotatably supported in the
housing 4 by means of bearings 5; a pulley 7 that is fixed to an end
portion of the shaft 6 that extends out frontward from the housing 4; a
rotor 8 that is fixed to the shaft 6 and that is disposed inside the
housing 4; a stator 20 that is fixed to the housing 4 so as to surround
the rotor 8; a pair of slip rings 12 that are fixed to a rear end of the
shaft 6, and that supply electric current to the rotor 8; a pair of
brushes 13 that slide on respective surfaces of the slip rings 12; a
brush holder 14 that accommodates the brushes 13; a rectifier 15 that is
electrically connected to the stator 20 so as to convert alternating
current that is generated by the stator 20 into direct current; and a
voltage regulator 16 that is mounted onto the brush holder 14, and that
adjusts magnitude of an alternating-current voltage that is generated by
the stator 20.

[0023] The rotor 8 includes: a field coil 9 that generates magnetic flux
on passage of an excitation current; a pole core 10 that is disposed so
as to cover the field coil 9, and in which magnetic poles are formed by
the magnetic flux; and the shaft 6, which is fitted centrally through the
pole core 10. Fans 11 are fixed to two axial end surfaces of the pole
core 10 by welding, etc.

[0024] The stator 20 is held from two axial ends by the front bracket 2
and the rear bracket 3, and includes: a stator core 21 that is disposed
so as to surround the pole core 10 so as to ensure a uniform gap from an
outer peripheral surface of the pole core 10 of the rotor 8; and the
stator winding 22, which is mounted to the stator core 21.

[0025] As shown in FIG. 4, the stator core 21 is a laminated core that is
formed into a cylindrical shape by laminating a predetermined number of
core segments that are formed by punching thin magnetic steel plates into
annular shapes, and integrating the laminated predetermined number of
core segments by welding, for example. The stator core 21 has: an annular
core back portion 21a; tooth portions 21b that each extend radially
inward from an inner peripheral surface of the core back portion 21a, and
that are arranged at a uniform angular pitch circumferentially; and slots
21c that are bounded by the core back portion 21a and adjacent tooth
portions 21b.

[0026] Here, the number of claw-shaped magnetic poles in the pole core 10
of the rotor 8 is twelve, and the number of slots 21c is seventy-two.
Specifically, the slots 21c are formed at a ratio of two slots per phase
per pole, and at a uniform angular pitch circumferentially (an electrical
pitch of π/6).

[0027] As shown in FIGS. 2 and 3, the stator winding 22 is configured by
connecting together output ends of the three phases of the first
three-phase stator winding 23 and the second three-phase stator winding
24 to connect the first three-phase stator winding 23 and the second
three-phase stator winding 24 in parallel.

[0028] The first three-phase stator winding 23 is configured by
wye-connecting a U1-phase winding 30, a V1-phase winding 31,
and a W1-phase winding 32. The U1-phase winding 30 is
configured by connecting in series a U1-1-phase winding portion 41
and a U1-2-phase winding portion 42 that have a phase difference of
30 electrical degrees. The V1-phase winding 31 is configured by
connecting in series a V1-1-phase winding portion 43 and a
V1-2-phase winding portion 44 that have a phase difference of 30
electrical degrees. The W1-phase winding 32 is configured by
connecting in series a W1-1-phase winding portion 45 and a
W1-2-phase winding portion 46 that have a phase difference of 30
electrical degrees.

[0029] The second three-phase stator winding 24 is configured by
wye-connecting a U2-phase winding 35, a V2-phase winding 36,
and a W2-phase winding 37. The U2-phase winding 35 is
configured by connecting in series a U2-1-phase winding portion 51
and a U2-2-phase winding portion 52 that have a phase difference of
30 electrical degrees. The V2-phase winding 36 is configured by
connecting in series a V2-1-phase winding portion 53 and a
V2-2-phase winding portion 54 that have a phase difference of 30
electrical degrees. The W2-phase winding 37 is configured by
connecting in series a W2-1-phase winding portion 55 and a
W2-2-phase winding portion 56 that have a phase difference of 30
electrical degrees.

[0030] An output end of the U1-phase winding 30 and an output end of
the U2-phase winding 35 are connected, an output end of the
V1-phase winding 31 and an output end of the V2-phase winding
36 are connected, and an output end of the W1-phase winding 32 and
an output end of the W2-phase winding 37 are connected. The first
three-phase stator winding 23 and the second three-phase stator winding
24 are thereby connected in parallel to configure the stator winding 22.

[0031] Next, a specific construction of the stator winding 22 will be
explained.

[0032] The U1-1-phase winding portion 41 is a three-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in a
first slot group that is constituted by the slots 21c at intervals of six
slots that include Slot Numbers 1, 7, etc., through 61, and 67. The
U1-2-phase winding portion 42 is a four-turn wave winding that is
formed by winding a conductor wire 29 into a wave winding in a second
slot group that is constituted by the slots 21c at intervals of six slots
that include Slot Numbers 2, 8, etc., through 62, and 68.

[0033] The V1-1-phase winding portion 43 is a three-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in a
third slot group that is constituted by the slots 21c at intervals of six
slots that include Slot Numbers 3, 9, etc., through 63, and 69. The
V1-2-phase winding portion 44 is a four-turn wave winding that is
formed by winding a conductor wire 29 into a wave winding in a fourth
slot group that is constituted by the slots 21c at intervals of six slots
that include Slot Numbers 4, 10, etc., through 64, and 70.

[0034] The W1-1-phase winding portion 45 is a three-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in a
fifth slot group that is constituted by the slots 21c at intervals of six
slots that include Slot Numbers 5, 11, etc., through 65, and 71. The
W1-2-phase winding portion 46 is a four-turn wave winding that is
formed by winding a conductor wire 29 into a wave winding in a sixth slot
group that is constituted by the slots 21c at intervals of six slots that
include Slot Numbers 6, 12, etc., through 66, and 72.

[0035] The U2-1-phase winding portion 51 is a four-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in the
first slot group. The U2-2-phase winding portion 52 is a three-turn
wave winding that is formed by winding a conductor wire 29 into a wave
winding in the second slot group.

[0036] The V2-1-phase winding portion 53 is a four-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in the
third slot group. The V2-2-phase winding portion 54 is a three-turn
wave winding that is formed by winding a conductor wire 29 into a wave
winding in the fourth slot group.

[0037] The W2-1-phase winding portion 55 is a four-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in the
fifth slot group. The W2-2-phase winding portion 56 is a three-turn
wave winding that is formed by winding a conductor wire 29 into a wave
winding in the sixth slot group.

[0038] The U1-phase winding 30 is configured by joining a winding
finish portion of the U1-1-phase winding portion 41 and a winding
start portion of the U1-2-phase winding portion 42 by tungsten-inert
gas (TIG) welding, etc., and is a seven-turn winding. Similarly, the
V1-phase winding 31 and the W1-phase winding 32 are also
seven-turn wave windings. Then, the winding start portions of the
U1-1-phase winding portion 41, the V1-1-phase winding portion
43, and the W1-1-phase winding portion 45 are joined by TIG welding,
etc., to form the first three-phase stator winding 23.

[0039] The U2-phase winding 35 is a seven-turn wave windings that is
configured by connecting the U2-1-phase winding portion 51 and the
U2-2-phase winding portion 52 in series. Similarly, the
V2-phase winding 36 and the W2-phase winding 37 are also
seven-turn wave windings. Then, the winding start portions of the
U2-1-phase winding portion 51, the V2-1-phase winding portion
53, and the W2-1-phase winding portion 55 are joined by TIG welding,
etc., to form the second three-phase stator winding 24.

[0040] In addition, winding finish portions of the U1-2-phase winding
portion 42 and the U2-2-phase winding portion 52 are joined by TIG
welding, etc., winding finish portions of the V1-2-phase winding
portion 44 and the V2-2-phase winding portion 54 are joined by TIG
welding, etc., and winding finish portions of the W1-2-phase winding
portion 46 and the W2-2-phase winding portion 56 are joined by TIG
welding, etc., to form the stator winding 22.

[0041] Next, operation of the automotive alternator 1 that is configured
in this manner will be explained.

[0042] First, an electric current is supplied from a battery (not shown)
through the brushes 13 and the slip rings 12 to the field coil 9 of the
rotor 8 to generate magnetic flux. Magnetic poles are formed in the
claw-shaped magnetic poles of the pole core 10 by this magnetic flux.

[0043] At the same time, rotational torque from an engine is transferred
to the shaft 6 by means of a belt (not shown) and the pulley 7 to rotate
the rotor 8. Thus, rotating magnetic fields are applied to the stator
winding 22 in the stator 20 to generate electromotive forces in the
stator winding 22. The alternating currents that are generated by these
electromotive forces are rectified into a direct current by the rectifier
15, to charge the battery, or be supplied to an electrical load.

[0044] In the stator winding 22 that is configured in this manner, the two
winding portions of each of the phases that are connected in parallel all
have seven turns, suppressing the generation of cyclic currents in the
parallel circuit portions.

[0045] As shown in FIG. 5, seven conductor wires 29 are housed inside each
of the slots 21c. Thus, the number of conductor wires 29 that are housed
in each of the slots 21c is equal, suppressing the formation of
unevenness on the inner circumferential surfaces of the coil end groups
of the stator winding 22. Generation of wind-splitting noise that results
from interference between the rotating rotor 8 and the inner
circumferential surfaces of the coil end groups is thereby suppressed.

[0046] Because the neutral points between the first three-phase stator
winding 23 and the second three-phase stator winding 24 are each
configured by connecting three conductor wires 29, work for connecting
together the neutral points between the first three-phase stator winding
23 and the second three-phase stator winding 24 is extremely complicated.
In the present invention, because the neutral points between the first
three-phase stator winding 23 and the second three-phase stator winding
24 are not connected with each other, the complicated connecting work can
be omitted, facilitating manufacturing of the stator 20.

[0047] In the respective phase windings, because two winding portions that
are offset by 30 electrical degrees, such as the U1-1-phase winding
portion 41 and the U1-2-phase winding portion 42, for example, are
connected in series, magnetomotive pulsating forces can be reduced,
reducing magnetic noise.

[0048] In the respective phase windings, because the turn counts in the
two winding portions that are connected in series, such as the
U1-1-phase winding portion 41 and the U1-2-phase winding
portion 42, for example, are different, output from the automotive
alternator 1 can be increased.

[0049] Here, results when output characteristics of the present automotive
alternator 1 were measured are shown in FIG. 6. Moreover, in FIG. 6, the
solid line represents the output characteristics of the present
automotive alternator 1, and the broken line represents the output
characteristics of a comparative automotive alternator. The comparative
automotive alternator is configured in a similar manner to that of the
present automotive alternator 1 except that a comparative stator winding
60 that is shown in FIG. 7 is used.

[0050] As can be seen from FIG. 6, it has been confirmed that the
automotive alternator 1 can achieve higher output than the comparative
automotive alternator throughout a range of rotational speeds.

[0051] Next, a specific construction of the comparative stator winding 60
will be explained with reference to FIGS. 7 and 8. Moreover, FIG. 7 is a
connection diagram for a stator winding according to the comparative
example, and FIG. 8 is a partial end elevation that explains a state in
which conductor wires are mounted into a stator core in an automotive
alternator according to the comparative example. Moreover, FIG. 8
represents a state in which an annular stator core is cut open and spread
out in a plane.

[0052] A U1-1-phase winding portion 71 is a four-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in the
first slot group. A U1-2-phase winding portion 72 is a three-turn
wave winding that is formed by winding a conductor wire 29 into a wave
winding in the second slot group.

[0053] A V1-1-phase winding portion 73 is a four-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in the
third slot group. A V1-2-phase winding portion 74 is a three-turn
wave winding that is formed by winding a conductor wire 29 into a wave
winding in the fourth slot group.

[0054] A W1-1-phase winding portion 75 is a four-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in the
fifth slot group. A W1-2-phase winding portion 76 is a three-turn
wave winding that is formed by winding a conductor wire 29 into a wave
winding in the sixth slot group.

[0055] A U2-1-phase winding portion 81 is a four-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in the
first slot group. A U2-2-phase winding portion 82 is a three-turn
wave winding that is formed by winding a conductor wire 29 into a wave
winding in the second slot group.

[0056] A V2-1-phase winding portion 83 is a four-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in the
third slot group. A V2-2-phase winding portion 84 is a three-turn
wave winding that is formed by winding a conductor wire 29 into a wave
winding in the fourth slot group.

[0057] A W2-1-phase winding portion 85 is a four-turn wave winding
that is formed by winding a conductor wire 29 into a wave winding in the
fifth slot group. A W2-2-phase winding portion 86 is a three-turn
wave winding that is formed by winding a conductor wire 29 into a wave
winding in the sixth slot group.

[0058] A U-phase winding 61 is configured by connecting in series a
winding portion in which the U1-1-phase winding portion 71 and the
U2-1-phase winding portion 81 are connected in parallel and a
winding portion in which the U1-2-phase winding portion 72 and the
U2-2-phase winding portion 82 are connected in parallel. A V-phase
winding 62 is configured by connecting in series a winding portion in
which the V1-1-phase winding portion 73 and the V2-1-phase
winding portion 83 are connected in parallel and a winding portion in
which the V1-2-phase winding portion 74 and the V2-2-phase
winding portion 84 are connected in parallel. A W-phase winding 63 is
configured by connecting in series a winding portion in which the
W1-1-phase winding portion 75 and the W2-1-phase winding
portion 85 are connected in parallel and a winding portion in which the
W1-2-phase winding portion 76 and the W2-2-phase winding
portion 86 are connected in parallel.

[0059] As shown in FIG. 7, the stator winding 60 is configured by
wye-connecting the U-phase winding 61, the V-phase winding 62, and the
W-phase winding 63, and forms an electrical circuit that is approximately
equivalent to that of the stator winding 22 described above.

[0060] The comparative automotive alternator is configured using the
stator winding 60 instead of the stator winding 22. In the stator winding
60 that is configured in this manner, the turn counts of the two winding
portions that constitute the respective parallel circuit portions are
also equal, suppressing the generation of cyclic currents in the parallel
circuit portions. Because two winding portions that are offset by 30
electrical degrees are connected in series in each of the phase windings,
magnetomotive pulsating forces can be reduced, reducing magnetic noise.

[0061] However, in the automotive alternator according to the comparative
example, slots 21c in which eight conductor wires 29 are housed and slots
21c in which six conductor wires 29 are housed are arranged alternately,
as shown in FIG. 8. Thus, unevenness arises on the inner circumferential
surface of the coil end groups of the stator winding 22, increasing
wind-splitting noise that results from interference between the rotating
rotor 8 and the inner circumferential surfaces of the coil end groups.

[0062] Moreover, in each of the above embodiments, explanations are given
for automotive alternators, but the present invention is not limited to
automotive alternators, and similar effects are also exhibited if the
present invention is applied to automotive rotary electric machines such
as automotive electric motors, automotive generator-motors, etc.

[0063] In the above embodiment, phase windings are configured by
connecting in series two winding portions that have a phase difference of
30 electrical degrees, but the phase difference between the two winding
portions that are connected in series is not limited to 30 (electrical)
degrees.

[0064] In the above embodiment, respective phase windings of the first and
second three-phase stator windings are configured by connecting a
four-turn winding portion and a three-turn winding portion in series, but
the turn counts of the two winding portions that are connected in series
are not limited to four turns and three turns, provided that they are
different than each other.